SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dc56493398f230064c588d44181d67dd0b5dfc876662998831f6694c8305a69' 
  AND token = 'qqmO/mszKothcirU1Bp28LJViCTzhLOE1/tzg9BxFDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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