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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87fe7835b0a2e7cac35e1bc15d20dbdd9eacc395739c0312da33e74d1f3cc45a' 
  AND token = 'Z+lIhuEMhKC7LCreG/dU2G4orz3ZN0ZKOvI4Ark5kIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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