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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e80286369b45a8bb04f67c3f69fd4c89951ad25a17ccc3cda746bea81b22a1c2' 
  AND token = 'O7pOXTNY1rFlEqLx5SE3Y2iuhcIa2tnKdXA8NdCcKB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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