SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a7b6b1a314826fdcffaa4717d4045c7ec11e9ded38e5569ecbe161ff393b252' 
  AND token = 'Y3nzp/2R3hhADL5XyOgT3LZuKk+dCzNwEszXhwvmIIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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