SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '50147787f9263285afb7b298b6905254dd492c48e2b1c2c55ef714ce06c1918a' 
  AND token = 'MfU3yUP82YRCNo1+8fnBAuLJG0zCOAtRantN9V7qnwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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