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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bb7f9a1ef6b95a733810c9b7646d6479e1ef5a3cc200740c2e1e79cdb0cad7a' 
  AND token = 'Ng/AA0Gv08pOFYV0vpOOZH3Jf08pFWKYFWGvB1wuKMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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