SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b14ae34c6594afde33f0caab73e9012f76fcc873cc5eb4226e18330c63d251ac' 
  AND token = 'sQbqGDpuBjhM+H8xf8zjbQC38wJTCynOh1U/Jt93VL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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