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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820edfcd6f5a9c81983ab3e1557343541013054129847a9521e313445960cc6c' 
  AND token = 'ILHDoYQkB3gfZ3x726ZRLXk+znUEc1c/2XjQU7anv+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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