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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0bd4ef769ad78d53dde91b96124caf79c04ba40eb8a687f6aea099643cc9a7d' 
  AND token = 'MVmobmlzfXlynSYp/JIysM6+Bf0bY1mFOcI48VQ1Sz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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