SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a9c9e1cabf1cbbd9fefd202329e6b024603b3ad7e43c96227db0eacdb42887a' 
  AND token = 'xQ5bTUs9xnnd91JwA1m0eTYdsJT88IeCJk4UFZ4//44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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