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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d77a0dfd845eef9eced7af5833a135920c9e628304eeb8c5bee16a57e4468c6' 
  AND token = '6KimedBLj34h5ZfzWZGCqDBOOowc8hI9jxyydEq/0tE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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