SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cad575dbfcc7826b32433c06fd3b7626572323319288086c1d42b73e20d65588' 
  AND token = 'e/mNVS4z3GE4KLL9LxFl8BSq9tLd63YxNBGPmq5TNwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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