SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b57d8832e50cfc0a5b031beb7c281eadbd36840e36b692115baaa5333aa324e5' 
  AND token = 'Qewdl9sGbSQJaArpL9atpocE1rvrFdFarmm594phfV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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