SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb6529669c55d21f4617e2e257275d6b1c11ee9a2976f0e8f3e0210d65dab280' 
  AND token = 'S4oPKxUki3/1Ag4jwDOZC09fDFUgol21w3WTixQ87iA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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