SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b5c66747c33c5911aa9476bceb45010a988281a3eed4c3efa0476c23c001948' 
  AND token = 'M1p3PLSPCQuMMQKNutA9SKLxYc7nPlUaLVZSqBcpQhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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