SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0320436d66e0d15c6ef31e269a5e47fddf3f6101fe960de8bc897508a4b43bcc' 
  AND token = 'SAWMqB8omSzb1jMLER+CCk31SOMFnjwYUVSdpXSlDAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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