SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2475993fc4351bf4302692b2f452a6a4fb6a60cc86e8108579b8207b05ba1d01' 
  AND token = 'd0GZ7GVFE1nmAij4hNVs6jGFdb5rE2yT8BNK0Danl44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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