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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a15fc3e8bbb70409e4c8fb1930c120a5633eded6d63d4efa9c4072ad97911a97' 
  AND token = 'OfTf7O0ruSUiFBZQVQKFQ6BAQBkDsPTMloHzCG3Yz5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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