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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ed1e8693ae8017fc3f93f9c1588468e5ac577f57e1eecdda750a43db8a5ef5d' 
  AND token = 'crsMSBD9ELcE9hYVOVwxUrAA7W4MUTEGGzeZ+bf5nAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}