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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8936f3fdaac1a8b0f8f8b2ebc2a1706c92648404de37f06a5afcf9dca6d4f4c' 
  AND token = 'OEYZMksyX5f3l6EsKFADzbRoYn0lagjmUNvnDAJlmMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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